1H-Pyrazolo[5,1-c]-1,2,4-triazoles are compounds which are useful as couplers, especially magenta couplers, for silver salt color photography. In contrast to conventional pyrazolone type magenta couplers the novel couplers of the present invention are free from color stain attributed to side absorption which the formed dyes have in the vicinity of 430 nm. The utility thereof is described, for example, in JP-B-48-30895 (the term "JP-B" as used herein means an "examined Japanese patent publication"), U.S. Pat. No. 3,725,067, British Patent 1,252,418, Journal of the Chemical Society, Perkin I, 2047-2052 (1977), JP-A-62-209457 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), and JP-A-62-229146.
Methods for synthesizing the foregoing novel couplers are described, for example, in the above-cited Journal of the Chemical Society, U.S. Pat. No. 3,725,067, WO 86/01915, JP-A-61-18768, JP-A-62-10068, JP-A-62-10069, JP-A-62-195368, JP-A-62-209457, JP-A-62 228066, JP-A-62-229146 and JP-A-62-252773. Specific examples of methods for synthesizing the couplers include the methods disclosed in the following publications: ##STR4##
However, these methods of synthesis suffer from defect(s) such that poisonous thiocarbohydrazide has to be employed as a starting material, a yield rate of the hydrazinopyrazole produced is low, and the produced hydrazinopyrazole can have high solubility in water depending on the kind of substitutent R which makes it very difficult to handle. When using 1H-pyrazolo[5,1-c]-1,2,4-triazoles as magenta couplers for photography, additional defects include the fact that the step of eliminating X=COOEt or CN with an acid, the number of steps is increased, and what is worse, the decarboxylation reaction is difficult to control. Moreover, when R is a group other than one which is attached to the pyrazole nucleus via its carbon atom, the hydrazinopyrazole cannot be synthesized at all, or can be synthesized only in a low yield rate.